Pleuroparenchymal fibroelastosis: a spectrum of histopathological and imaging phenotypes.

Pleuroparenchymal fibroelastosis (PPFE) is a rare condition characterised by predominantly upper lobe pleural and subjacent parenchymal fibrosis, the latter being intra-alveolar with accompanying elastosis of the alveolar walls. The aim of this study was to review cases fulfilling published imaging and histological criteria, and identify any common clinical features that may suggest an underlying aetiology for a condition that has previously been regarded as idiopathic. Of 12 patients (seven females, median age 57 yrs), the presenting symptoms were shortness of breath (11 out of 12 patients) and dry cough (six out of 12 patients). Seven patients reported recurrent infections during the course of their disease. Five demonstrated nonspecific autoantibody positivity. Two patients had a family history of interstitial lung disease (ILD). High-resolution computed tomography features of lung disease remote from the pleuroparenchymal changes were present in six out of 12 patients (coexistent fibrosis, n=5; bronchiectasis, n=1). Of seven patients with tissue sampled from the lower lobes, four patients showed less intense PPFE changes (one with additional features of hypersensitivity pneumonitis) and three showed usual interstitial pneumonia. PPFE is a distinct clinicopathological entity, with clinical data suggesting a link to recurrent pulmonary infection. Genetic and autoimmune mechanisms may also contribute to the development of these changes. PPFE may also present with more diffuse involvement than previously reported, and coexist with different patterns of ILD.

Respiratory bronchiolitis with fibrosis. High-resolution computed tomography findings and correlation with pathology.

BACKGROUND: Recent pathology studies report that the lungs of cigarette smokers may demonstrate small localized subpleural foci of interstitial fibrosis associated with emphysema. Pathologically, this lesion has been termed smoking-related interstitial fibrosis, respiratory bronchiolitis-interstitial lung disease (ILD) with fibrosis, or airspace enlargement with fibrosis, but it is commonly misinterpreted on imaging and biopsy as a diffuse fibrosing interstitial pneumonia. The high-resolution computed tomography (HRCT) appearance of this process has not been defined. OBJECTIVES: We describe HRCT imaging of seven patients with this lesion present histologically. MEASUREMENTS AND MAIN RESULTS: HRCT features consisted of patchy areas of mild reticulation around predominantly subpleural upper/mid zone emphysematous changes in all cases, with variable patchy ground-glass change in six cases. Pathologically, there were distinctly circumscribed foci of dense, often hyalinized, interstitial fibrosis mixed with emphysema; variable numbers of smoker's macrophages were present in the airspaces. The fibrosis was confined to the subpleural regions. Three patients with follow-up information were clinically stable. CONCLUSIONS: These data suggest that a CT pattern of patchy areas of reticular changes about predominantly upper zone emphysematous spaces may be seen in smokers who do not have clinical evidence of a diffuse ILD. We propose that this lesion be called respiratory bronchiolitis with fibrosis (RBF) to avoid confusion with other forms of ILD. RBF probably accounts for some of the cases of ILD seen in large radiologic surveys of smokers. The pathology literature indicates that RBF either has no functional effects or at worst represents mild, usually nonprogressive disease, and hence separation from other, more serious, forms of ILD is important. Recognition of this lesion on imaging may obviate the need for lung biopsy.

Idiopathic dendriform pulmonary ossification.

Diffuse dendriform pulmonary ossification is a rare disorder characterized by widespread pulmonary ossification distributed in a characteristic branching pattern. It is usually associated with chronic interstitial inflammation and fibrosis but may occasionally be idiopathic. The underlying pathogenesis remains uncertain. Computed tomography findings characteristically show fine branching heterotopic bone formation within the lungs, often in a lower lobe distribution. A case of idiopathic dendriform ossification is described in a 34-year-old man who presented for investigation of hemoptysis.